Clinical presentation as a guide to therapy for travelers' diarrhea.

To better define the role of antimicrobial therapy among U.S. travelers in Mexico, clinical and nonculture laboratory parameters were compared for 56 patients with shigellosis and 204 others with diarrhea of other causes. The presence of fever, stool mucus and blood, and fecal leukocytes were significantly more common among patients with shigellosis (p less than 0.001) who also tended not to present with mild diarrhea (p less than 0.05). However, clinical and laboratory parameters were either too insensitive or too nonspecific to be useful in identifying most cases of shigellosis or in excluding the likelihood of its presence. Patients with mild clinical presentations, regardless of etiology, experienced resolution of disease sooner than those with moderate to severe presentations (p less than 0.01), but withholding therapy from patients with mild presentations resulted in 48% of these patients remaining ill at the end of 48 hours. Based on these findings, the authors advise empiric use of antimicrobial agents in travelers with diarrhea associated with fever, bloody stools, or fecal leukocytes, and for all travelers with moderate and severe diarrhea. If therapy is withheld from patients with initially mild presentations, a proportion might still require therapy, possibly an antimicrobial agent, for optimal control of symptoms.